This invention relates to a motion compensated predictive coding/decoding system of picture signals suitable for coding/decoding moving pictures.
There is a coding/decoding system for television conference in conventional coding/decoding systems by motion compensated prediction. In this system, a picture to be coded/decoded is constituted by about 352.times.240 pixels and a motion range in the picture to be motion compensated is .+-.7 pixels or so horizontally and vertically. When an picture size is small like this, one processor is enough to perform real-time coding/decoding of the picture by compensated prediction.
However, in NTSC (National Television System Committee) system of 704.times.480 pixels and HDTV (High Definition Television) system of 1920.times.1080 pixels, it is hard for one processor to coding/decoding a moving picture by motion compensated prediction, due to the capacity of the processor.
Therefore, a plurality of processors are employed for coding/decoding a picture of large size. As shown in FIG. 1, a picture supplied to a frame memory FM is divided into block data each having 16.times.16 pixels by a blocking circuit B. Those block data are supplied to processors P0 to P3 respectively. The processors respectively calculate motion vectors and perform motion compensated predictive coding in parallel using image memories M0 to M3. Coded data are multiplexed by a multiplexer M.
Such system however has drawback as follows. FIGS. 2A and 2B show a frame which is the total area occupied by a picture. Data corresponding to an area A is coded/decoded by the processor P0 with the image memory M0, and so on. When there is an object which is moving across a border between two areas C and D, the processor P2 which only governs the image memory M2 cannot use the data stored in the image memory M3 governed by the processor P3, as a data for motion compensated prediction. This result in discontinuity on the border of the areas processed by the processors P2 and P3 so that a picture displayed on a television is degraded.